Vehicle brake mechanism



Feb. 21, 1933. R EVANS 1,898,434

VEHICLE BRAKE MECHANI SM Original Filed Sept. 4, 1923 4 Sheets-Sheet l ATTORNEYIS Feb. 21,1933. E. R. EVANS VEHICLE BRAKE MECHANISM OriginalFiled Sept. 4. 1923 4 Sheets-Sheet 2 MS mm 3m Ni x w? Wm H v g w i W V.f B w m \r Feb. 21, E; EVANS 1,898,434

VEHICLE BRAKE MECHANISM Original Filed Sept. 4. 1923 4 Sheets-Sheet 3QEQQQN k G v R g a \q .4 F I R \\\x\ t? I n I j I INVENTOR, N5411277257019 A TTORNEYS Fab. 21, 1933. E R EVANS 1,898,434

VEHICLE BRAKE MECHANISM Original Filed Sept. 1923 4 Sheets-Sheet 4 Z9INVENTOR.

:7 wmmwwwmwmg ATTORNEY/S Patented Feb. 21, 1933 UNITED STATES EDWIN n.Evens, or CHICAGO, ILLINOIS VEHIGLE BRAKE MECHANISM OriginaL applicationfiled This invention relates to vehicle brake mechanisms andparticularly relates-to mechanisms including both front and rear wheelbrakes. This application is. a divisional of 5, copending ap )licationSerial Number 660,855, now Patent ho. 1,648,168, November 8, 1927 andReissue #17588.

The invention consists in a provision for properly proportioning thebraking. forces reapplied to the several wheels from a commoncontrolling member.

In the drawings: I Figure 1 is a plan view of a vehicle chassis equippedwith the improved. brake mecha- 15: nism Figure 2 is a sectional view ofthe same on line 22 of Figure l;

Figure 3 is a cross section on line 3-3 of Figure. 1 showing therelation-of the clutch 20- controland the brake control mechanisms;

Figure 4 is a verticalsectional View of the same on line 4-4 of Figure3;

Figure 5 is a section on line 55of Figure 3 showing primarily the brakecontrol pedaland'connected parts;

Figure 6 is a section on line 6 6 of Figure 1 showing one of the frontwheel brake mechanisms Figure 7 is a vertical section on line 77 ofFigure 6; i

Figure 8is a section on line 88 ofjFigure 7 showing the adjustablemounting for the brake shoes;

Figure 9 is a detail sectional view taken upon line 99 of Figure 1showing mechanism for equalizing the braking force transmitted to thetwo rear wheels.-

In these views, the reference character: 1 designates the frame of amotor vehicle and 2 and 3 the front and back wheels thereof,

each'of said wheels being provided with a brake drum 4. is the frontaxle, 6 the engine,'7 the clutch housing, 8 the brake control pedal and9 the clutch control pedal. The pedal 9 is mounted in the clutch housing7 and within said housing carries a pair of lugs 11 upstanding atopposite sides of the transmission shaft 12 to engage trunnions 13 uponthe clutch release collar 14. Preferably 50 the shaft comprises portionsat opposite September 4, 1923, Serial No. 660,855. Divided and thisapplication filed May 5, 1924: Serial No. 711,278. Renewed September 25;1929;

sides of the transmission shaft 12 and rigidly connected by a yokemember 15 which is downwardly offset to clear the shaft 12 and collar14. The lower end portion of the brake control pedal 8 forms a casing 16which is journaled upon the shaft 10 between the clutchpedal lever 9 andthe housing 7. VVithin said casing, a bevelled pinion 17 is journaledupon a stub shaft 18 carried by said casing in a radial relation to theshaft 10. Said pinion is oppositely engaged, within said casing, bysegmental bevel gears 18*, one of which is fast upon a short tubularshaft- 19- journaled upon the shaft 10 exteriorly of the housing 7, oneof the front brake control levers 19- also being fast upon said tubularshaft. The other gear 18 is fast upon a longer tubular shaft 20, alsojournaled upon the shaft 10 and extending into said housing. Ayoke bar21 offset downwardly below the yoke 15, rigidly connects the shaftthrough a pull rod 27 pivoted to said lever with a tubular shaft 22ournaled upon the shaft 10 at the opposite side of the transmissionshaft 12, said shaft 22 projecting exteriorly of the casing. 7 to mountthe other front brake control lever 19. The levers 19 arepivotallyengagedby rods 24 which extend forwardly to pivotally engage arms 25upon; the cam shafts 26 of the front wheel brakes. The brake controlfoot lever 8 is adapted to actuate the rear brakes through a pull rod27v pivoted'to saidlever just above the gear casing 16. Saidrod extendsrearwardly to engage an arm 28 integrally depending from a casing 29journaled upon the adjacent'ends of'two aligned rock shafts 30 mountedtransversely of the frame 1. \Vithin the casing 29, theshafts30 rigidlycarry gear segments 31 which mesh with a bevel pinion 32 journaledbetween said segments upon a stud shaft 33 carried by the casing 29. Theouter ends of the rock shafts 30 are respectivelyconnected by pull rods34 to the cam shaft 35of the rear brakes.

Consideringnow the operation of the in- .vention' as so far described,upon actuation of the foot lever 8, the resultant rocking of the casing16, rigidly carried by, the lower end'of.- said lever, causesthe pinion17 carried by said casing to form through its engagement with the gearsegments 18 a means for subjecting said segments to an equalized rockingmovement. As is well understood, the pinion 17 will adjust itselfrelative to the segments 18 so as to equalize the effort transmittedthrough each of said segments. This equalized effort is transmitted fromsaid segments through the pull rods 24 to the front brakes. Theconcentric mounting of the brake shaft 20 and clutch shaft 10 simplifiesthe mechanism and further produces a compact unit assembly for the mainclutch and brake rock shafts. This assembly is made possible primarilyby employment of the offset connections 15 and 21 between the portionsof said shafts at opposite sides of the engine shaft.

Equalization of the braking effect acting upon the two front wheels anda similar equalization as regards the rear brakes is as sured by thegearings 17, 18 and 31, 32. There will presently be described aprovision for equalization of the total efforts applied to the front andrear wheel brakes or establishment of a desired proportion between saidefiorts.

Describing now the specific mounting of the brake shoes of each brake,36 designates a pair of complementary semi-circular brake shoesinteriorly engageable with each drum 4. The upper ends of said shoes areformed with adjacent pivot bearings 37 in which are respectively engagedcylindrical pivot 1nembers 38. As is best seen in Figure 7, saidbearings have openings in their opposing faces, said openings being of alesser transverse extent than the interior diameter of the bearings sothat the pivot members 38 cannot escape from the bearings through saidopen ings. Between said bearings there is mounted a wedge membercomprising a cylindrical body 39 having diametrically opposed ribs 40,the edges of which incline oppositely to the axis of the wedge member.Said ribs project through the lateral openings in the bearings 37 andengage in grooves respectively formed in the pivot members 38, saidgrooves having their bottom faces inclined correspondingly to the edgefaces of said ribs. The wedge body 39 has a threaded extension 42engaged by an adjusting nut 43 mounted in a supporting bracket 44. Thelatter is secured to a plate 45 forming a closure for the brake drum.The wedge body is formed with upwar ly and downwardly projecting splines46 which engage in spline ways 4-. formed as integral projections fromthe bracket 44, above and below the wedge member and between thebearings 37. Thus the wedge member is held from rotation but is free toslide in parallelism with the pivotal axes of the two brake shoesresponsive to tightening of the adjusting nut 43. The effect of suchtightening is to enter the wedge member 39, increasingly between thepivot members 88 so as to force the latter apart. The describedconstruction is such that the two brake shoes may turn freely upon thepivot members 38, the latter however, being restrained by the wedge ribs40 from any rotation.

In properly proportioning the total front and read braking effort thenuts 43 are first all tightened so as to firmly engage the brake shoeswith the brake drums. If it be desired to equalize the front and rearbraking efforts all of said nuts are then loosened to the same extent orthe nuts of the front and rear brakes may be differentially loosened toestablish a desired proportion between the front and rear brakingefforts. A ball detent 48 bearing upon the sleeve portion 43 of the nutand under stress of a spring 49 snaps into sockets 5O circumferentiallyspaced in said sleeve portion and serves both to retain the nut againstaccidental turning and to indicate to the operator a definite fractionalpart of a turn.

As shown in Figureb the cam shaft 26 is rotatably supported at its innerend by a bearing on the axle 5 closely adjacent the operating lever 25.At its outer end the shaft 26 carries a cam 55 which its between thevertically channeled head. portions 54 of the brake shoes 36. It will benoted that the center of the cam is substantially on the swiveling axisof the front wheel, as shown in Figure 6. The two shoes are drawntogether upon the cam 55 by their springs 56 and may move as a unit withthe cam 55, since there is a su icient free length of the shaft 26between its bearing on the axle and the cam 55 to allow such slightflexing as may be necessary to permit the movement required.

What I claim as my invention is In a front wheel brake operatingmechanism, in combination with a front wheel swiveled on the front axle,a brake drum carried by and swiveling with the front wheel, a pair ofbrake shoes interiorly expandable into engagement with said drum, a cambetween the free ends of said brake shoes having its centersubstantially on the swiveling axis of said front wheel, said cam beingbodily movable with said shoes relative to said drum, a cam shaftsupported at one end by said cam and rotatably supported at its innerend of said axle.

In testimony whereof I affix my signature.

EDWIN R. EVANS.

